Why is enteral nutrition often withheld in cases of congenital heart disease with decreased left-sided outflow?

In the context of congenital heart disease with decreased left-sided outflow, enteral nutrition is often withheld primarily due to the increased risk of necrotizing enterocolitis (NEC). NEC is a serious gastrointestinal condition that primarily affects premature infants, but it can also occur in infants with certain medical conditions, including congenital heart disease.

In patients with compromised circulation, like those with decreased left-sided outflow, the blood supply to the intestines may be inadequate. This can lead to ischemia, which is a condition where there is insufficient blood flow to the tissues, eventually resulting in necrosis, or death of the intestinal tissue. When enteral feeding is introduced, the digestive process increases blood flow to the intestines, which is already at risk due to poor perfusion. Consequently, this can exacerbate the likelihood of NEC developing.

The other factors, while important in other contexts, do not directly address the immediate risks associated with initiating enteral feeding in this particular group of patients. Aspiration risk is a concern in any infant with feeding difficulties, but it is not specific to congenital heart disease and does not constitute a primary reason for withholding feedings. High caloric requirements and increased metabolic demand are valid considerations but are typically managed through alternative feeding